The present invention relates to the art of interactive image-guided surgery. It finds particular application in conjunction with the planning stage of minimally invasive surgery performed in magnetic resonance imaging systems using free-hand guide devices to orient surgical tools such as biopsy probes or the like and will be described with particular reference thereto. It is to be appreciated, however, that the invention is also applicable to a wide range of imaging equipment and minimally invasive surgical procedures including those performed using CT scanners, ultrasonic, fluoroscopic, and other imaging devices and surgeries using those devices.
Heretofore, several systems have been proposed combining mechanical arm type mechanisms or free hand localizers together with human anatomy imaging devices for performing certain interventional surgical procedures such as, for example, the placement of catheters, drainage tubes, biopsy probes, or the like, within a patient""s body. In one such system described in U.S. patent application Ser. No. 08/980,337, filed Nov. 28, 1997 and assigned to the assignee of the instant application, a multi-jointed mechanical arm assembly is mounted in a fixed relationship to a CT scanner device. The mechanical arm assembly carries a surgical planning device for defining a physical trajectory extending from the mechanical arm assembly and through the body of a patient disposed on the CT scanner. In addition, the CT scanner includes a virtual needle display for planning the introduction of an object such as a biopsy probe into the patient from an entry point along a virtual trajectory shown on the display towards a virtual target point within the patient. The display includes a plurality of spaced transverse axial views taken through the patient including an image slice corresponding to the virtual needle entry point on the patient as well as a second transverse axial view of the patient taken on an image slice of the image volume data set corresponding to the target point within the patient. Other views of the patient that are co-planar with the virtual needle trajectory are useful for planning minimally invasive surgical procedures to avoid critical anatomical structures such as, for example, sensitive nerves, blood vessels or arteries, critical organs and the like. The system described also includes a manual virtual needle xe2x80x9cdepthxe2x80x9d control and provides a corresponding display of same to further assist interventionists during the planning stage.
Although the above system and others have met with success and provide adequate results, the displays of the virtual tool path trajectory are not updated in real time to follow localizer motion. More particularly, in order to provide the most complete and accurate virtual representation of the patient""s anatomy and virtual tool trajectory extending therethrough, the system performs a series of interpolation steps to develop the multiple image planes co-planar with the virtual needle trajectory for display based on an initially acquired image volume data set.
Of course, numeric interpolation requires time. This being the case, the displays presented to an interventionist often xe2x80x9clagxe2x80x9d quick gross motions of the mechanical arm assembly, and/or the surgical planning tool carried thereon. Another drawback of numerical interpolation, particularly when only a limited number of image slices are available, is that the overall image is degraded and the image appearance typically changes. This makes interpretation of the image more difficult and visualization of the procedure or planning less direct.
It is therefore desirable to provide a system for generating an essentially xe2x80x9creal timexe2x80x9d set of displays showing a virtual needle trajectory extending through virtual anatomy for planning image-guide interventional procedures. Preferably, there is little or no noticeable lag time between quick motions of the localizer planning device and the one or more virtual displays thereof.
In addition, it would be desirable to provide a system that generates a second display of an area of a first display selected by an interventionist by placing a plurality of graphical point symbols in the first display. Preferably, the second display is derived directly from a first image volume data set collected from the patient so that further re-scanning of the patient is unnecessary. Alternatively, the second display is based on an interpolation of the first image volume data set. Still alternatively, the second display is derived from a second image volume data set collected from the patient during a second scan of the patient. Preferably, the area of the patient scanned during the re-scan is bounded by the plurality of graphical point symbols.
Still in addition, it would be desirable to provide a system that generates a vertical bulls-eye target to enable visualization of the correctness of motion of a localizer device relative to a patient in size and/or color as the surgical tool carried on the localizer device first becomes aligned with the trajectory and then as the device reaches the target point.
The present invention provides a new and improved interface system for use with imaging devices to facilitate real time visualization of image-guided interventional procedure planning which overcomes the above-reference problems and others.
In accordance with the present invention, a method of planning a surgical procedure for inserting an object into a patient along a surgical planning trajectory from an entry point on the patient to a target point within the patient is provided. Using an imaging device, a patient is scanned to generate a first image volume data set of a first area of the patient. The image volume data set is formed of a plurality, preferably five (5) parallel two-dimensional image slices of the patient spaced apart along an axial axis aligned substantially with the head-to-toe axis of the patient. Using a human-readable display device associated with the imaging device, the first sectional image of the patient based on the first image volume data set is displayed. A second scan of the patient using the imaging device is planned with an operator interface device associated with the imaging device. A plurality of graphical point symbols are placed in the first sectional image of the patient displayed on the display device. The plurality of graphical point symbols define a second area of the patient to be subject of the second scan to generate a second image volume data set.
Further in accordance with the present invention, a second scan of the patient is performed using the imaging device to generate the second image volume data set of the patient. The second image volume data set is derived from the second area of the patient and is substantially bounded by the plurality of graphical point symbols placed in the second scan planning step.
In accordance with a more limited aspect of the invention, indicia are displayed on the display device of a position of each of the plurality of graphical point symbols relative to a plane through the first image volume data set defining the first sectional image. The indicia include first indicia indicating first ones of the graphical point symbols that are located between the plane on the display device and a human observer of the display device. Second indicia indicate second ones of the graphical point symbols that are located behind the plane of the display device relative to the human observer of the display device. Third indicia are displayed indicating a relative distance between the graphical point symbols and the plane.
In accordance with yet a further aspect of the invention, the step of planning the second scan of the patient by placing the plurality of graphical point symbols includes placing a first graphical point symbol in the first sectional image representative of a target point for an interventional surgical procedure on the patient. Further, the step of planning the second scan of the patient includes placing a second graphical point symbol in the first sectional image representative of an entry point before the interventional procedure on the patient.
In accordance with a still further aspect of the invention, the second scan of the patient is planned to generate a second sectional image of the patient orthogonal to a line connecting the entry point to the target point. Alternatively, the second scan of the patient is planned to generate the second sectional image of the patient parallel to the line connecting the entry point to target point.
In accordance with a second embodiment of the invention, an interface system is provided for use with an associated imaging device. The interface system is selectively operative to execute a scan of a patient to generate a first image volume data set of the patient. The interface system includes a human-readable display device associated with the imaging device for selectively displaying a plurality of first image slices of the patient taken from the first image volume data set. In addition, an operator interface device is provided in association with the imaging device. The operator interface device is operative to define spatial properties of a second set of image slices to be taken from the first image volume data set. The spatial properties of the second set of image slices to be taken from the first image volume data set are defined by selectively placing a plurality of graphical point symbols in the plurality of first image slices of the patient displayed on the display device.
In accordance with a further aspect of the second embodiment of the invention, the interface system includes interpolating means for generating the second set of image slices by interpolating the first image volume data set. In addition, means are provided for generating the second set of image slices as a maximum intensity projection image of the first image volume data set. The maximum intensity projection image represents a three-dimensional rendering of selected tissue within the patient.
It is a primary advantage of the present invention that visualization information is provided on a human-readable display monitor in substantially real time to track the motion of a localization device relative to a patient""s body.
It is another advantage of the present invention that a set of graphical symbols are provided for display on the human-readable display monitors. The graphical symbols include indicia regarding the relative position of the virtual planning trajectory relative to the one or more image planes shown on the display device. Other graphical symbols include a symbol representative of a virtual localizer device, a target point within the patient""s body, an entry point showing a point of intersection between the patient""s body and the planning trajectory, and a pivot point for fully determining the image plane. When expedient, the pivot point is chosen to include some selected regions of interest in the imaging plane such as, for example, a blood vessel or other tissue to be avoided during the surgical procedure.
Still other advantages and benefits of the invention will become apparent to those skilled in the art upon a reading and understanding the following detailed description.